A compact X-band microstrip bandstop filter using stepped impedance line with open-end stepped impedance stubs

A new and miniature circuit configuration for wideband bandstop filter (BSF) operating at X-band range is proposed in this article. The distinct filtering characteristics of this novel transmission line filter are investigated theoretically and experimentally. The presented planar microstrip filter consists of a three-section stepped impedance resonator (SIR) paralleled with three open-circuited stepped impedance stubs (SISs). An instance with approximately 24.5% fractional bandwidth (FBW) at a mid-stopband frequency of 10.6 GHz is developed and presented. The proposed BSF is successfully realized in theory and verified by full-wave electromagnetic simulation and the experiment. The simulated and measured results are in excellent agreement.